One method for examining the gastrointestinal tract for the existence of polyps and other clinically relevant features that may provide an indication regarding the potential of cancer is performed by swallowing an imaging capsule that will travel through the gastrointestinal (GI) tract and viewing the patient's situation internally. In a typical case the trip can take between 24-48 hours, after which the imaging capsule exits in the patient's feces. Generally the capsule will be surrounded by non-transparent liquids therefore a radioactive material is used to image the patient and not a visible light source.
Typically the patient swallows a contrast agent to enhance the imaging ability of the imaging capsule. Then the patient swallows the imaging capsule to examine the gastrointestinal tract while flowing through the contrast agent. The imaging capsule typically includes a radiation source, for example including a radioisotope that emits X-rays or Gamma rays. The radiation is typically collimated to allow it to be controllably directed in a specific direction during the imaging process. In some cases the imaging capsule is designed to measure Compton back-scattering and/or X-ray florescence and wirelessly transmit the measurements (e.g. a count rate) to an external analysis device, for example a computer or other dedicated instruments.
In a typical implementation a radio-opaque contrast agent is used so that a position with a polyp will have less contrast agent and will measure a larger back-scattering count to enhance accuracy of the measurements. Alternatively, other methods may be used to image the gastrointestinal tract.
U.S. Pat. No. 7,787,926 to Kimchy, the disclosure of which is incorporated herein by reference, describes details related to the manufacture and use of such an imaging capsule.
The radiation source used in the imaging capsule should preferably have a long half-life so that it does not need to be used immediately after preparation, rather there would be sufficient time to ship a few imaging capsules to a clinic and have them applied without urgency, for example within a few days before they expire.
Generally a selected amount of radioactive material is placed in a radiation chamber in the imaging capsule. However since the radioactive material is generally a dense molecule it interferes with itself and blocks a large portion of the radiation from being emitted from the imaging capsule. Therefore it is desirable to have the radioactive material arranged differently in the radiation chamber to enhance the emission of radiation.